The present invention relates to a video display device, and particularly to a video display device preferably applied for a graphics accelerator to be used for displaying a video picture on a computer display.
There have been used video display devices such as illustrated in FIG. 5 or FIG. 6.
A prior video display device 1, illustrated in FIG. 5, comprises a frame buffer 2 for buffering graphics display data of a computer, a memory control section 3 for controlling data read/write of the frame buffer 2, a video data processing section 4 taking charge of video data processing such as color space conversion or picture size magnification/demagnification for generating video picture data from video data, and a display control section 6 for generating display signals to be displayed on a screen of a display device 5 according to the graphics display data and the video picture data.
In the prior art of FIG. 5, the video data are stored in an idle memory space, wherein the display data are not stored, of the frame buffer 2. The video data stored therein are read out by the memory control section 3, processed with the video data processing by the video data processing section 4 into the video picture data and displayed after synthesized with the graphics display data prepared in the frame buffer 2.
In the prior art of FIG. 6 having a similar configuration with the prior art of FIG. 5, the video picture data after processed in the video data processing section 4 are written in a part of the effective space of the frame buffer 2 to be synthesized with graphics display data prepared therein, and the data synthesized with the graphics display data and the video picture data are read out from the effective space to be displayed.
However, with the video display device 1 according to the prior of FIG. 5 or the prior art of FIG. 6, the video data can not be displayed when there is no or insufficient idle space in the frame buffer 2 for buffering the video data.
This is a problem.